Analysis of TIG Welding Arc Using Boundary-Fitted Coordinates

Abstract

The characteristics of argon arc in tungsten inert gas (TIG) welding have been studied by considering the electrode shape which has an effect on the current density distribution near the electrode tip. For including the electrode surface configuration into the solution domain, the boundary-fitted coordinate system was employed. Then, a non-rectangular computational region in the physical domain was transformed into a rectangular area with uniformly spaced grids in the computational domain using the second-order central difference method. With the geometric transformation coefficients, the finite difference equations were derived in the computational transformed domain. As the most critical boundary condition, the normal current density distribution entering an electrode surface was postulated by the Gaussian distribution in consideration of the geometry of the electrode shape. For examining the simulated results, the temperature profile was compared with the experimental measurement of the previous research. The transferring phenomena on the base plate, such as current density, heat flux, arc pressure and drag force, were also calculated, because they are necessary data for analysing the molten pool during welding.